This invention relates generally to Magnetic Resonance Imaging (MRI) systems, and more particularly, to Radio-Frequency (RF) coils in MRI systems.
In MRI, the RF receive coil is one of the most important hardware components in the imaging system. A special-purpose receive coil for a region of interest is typically used for reception to enhance the signal-to-noise ratio (SNR) at that region.
For RF receive coils, it is known to further increase SNR using quadrature reception. In quadrature reception, NMR signals are detected in two orthogonal directions, which are in the transverse plane or perpendicular to the main magnetic field. The two signals are detected by two independent individual coils that cover the same volume of interest. With quadrature reception, the SNR can be increased, for example, by up to √2 over that of the individual linear coils.
Known receive coils are designed to provide higher image SNR. Further, with the use of parallel imaging techniques, not only is higher image quality provided, but higher scan speeds are provided without corresponding reduction in SNR.
Sensitivity Encoding (SENSE) is one techniques for parallel imaging that uses multiple coils to scan faster. Using SENSE, spatial sensitivity information provided by each coil element of a multiple-coil array system is used to substitute for the information provided by the encoding gradient in the k-space, therefore saving scanning time. The aliased or wrapped images generated by omitting the k-space lines are reconstructed by spatial sensitivity information provided by coil elements. Systems having SENSE compatible coils typically include a number of coil elements, with each of the coil elements providing distinctive spatial sensitivity information.
SENSE imaging may be used in different imaging applications, for example, for breast MRI. Breast MRI provides, for example, higher sensitivity when compared to other modalities. Changing magnetic resonance techniques and updated clinical imaging protocols result in a need for RF coils for breast imaging that provide high-resolution images, provide fast scanning speed with the application of the SENSE technique, and facilitate image guided biopsy and needle localization. The SENSE technique can greatly reduce the scan time, but typically requires arrays of multiple receiver coils that surround the tissue of interest. Known coils dedicated to breast MRI have very limited SENSE capability, if any at all, limited coverage, reduced SNR, more complex designs or decoupling arrangements, and/or are configured having a closed coil geometry that is unable to provide or provides limited biopsy access. Thus, these known coil designs for breast imaging are often complex and do not provide adequate or sufficient openness of the coils to allow medial and lateral biopsy access.